1. Field of the Invention
This invention relates to automotive air conditioning systems and in particular to an air conditioning system having two outlets for supplying different quantities of cooling air to left hand and right hand sides of a passenger compartment of a motor vehicle.
2. Background Art
A prior art air conditioning system 20 for a vehicle 10 is shown in FIG. 1. The air conditioning system 20 has a single fan or blower 22 to force air received from an inlet 21 into a single distribution chamber 23. A left hand distribution conduit 11L is connected to the distribution chamber 23 for supplying air conditioned air to a passenger seat on the left hand side of the motor vehicle 10 and a right hand distribution conduit 11R is connected to the distribution chamber 23 for supplying air conditioned air to a passenger seat on the right hand side of the motor vehicle 10.
It is a problem with such a system that it is not possible to provide consistent independent airflow volume to the two rear occupants. If the flow from one of the two distribution conduits 11L, 11R is turned off or the airflow is reduced then the airflow volume from the other distribution conduit 11R, 11L will increase unless the blower speed is reduced and this causes a control problem for the system because unless the flow rate through the distribution conduits 11L, 11R is constantly measured and an electronic control system is used there is no way of accurately adjusting the blower speed to return the flow through the unadjusted distribution conduit 11L or 11R to its previous level.
One solution to this problem is to separate the flows through the two distribution conduits and use separate blowers for each distribution conduit 11L, 11R but this is an expensive option and requires the separate blowers to be arranged at the outlet from the distribution chamber which is inefficient or requires separate air conditioning units to be used for each distribution conduit 11L, 11R which is expensive.